FORTUNE: Former Google executive Nikesh Arora joined SoftBank last year to oversee the Japanese company’s investment strategy, a task overseen so far by the legendary SoftBank founder, Masayoshi Son. Before joining SoftBank, Arora had been the top business executive at Google, having risen in the search giant’s ranks after running its highly profitable European business. He started his career as an investment analyst and also worked at Deutsche Telecom, making him a fit in all sorts of ways for SoftBank, a communications and Internet company.

Besides the improbable achievement of becoming the most recognizable entrepreneurs in Japan, Son, known by the nickname “Masa,” has proven to be an extraordinary investor. He wagered early on Yahoo Japan and Alibaba. The latter investment alone may be one of the greatest investments ever, parlaying a bet of about $200 million into a stake worth in the neighborhood of $70 billion.

Arora says Son aims to turn his “hobby” of investing into a foundation for the future of SoftBank. Already, Arora has had a busy nine months. Since he joined the company SoftBank has made nine investments, including the recently announced $100-million stake the U.S. geolocation advertising technology company Banjo. Others include a $250-million stake in GrabTaxi, an Uber competitor in Southeast Asia; a $627-million investment in Snapdeal.com, an Indian e-commerce company; and the $90 million SoftBank invested in housing.com, a property site in India.

SoftBank also was rumored to have attempted to acquire the ailing film studio DreamWorks Animation, a deal that was said to collapse just before it was done.

Son surprised the technology and investing world earlier this week by announcing that Arora would become SoftBank’s president in June, making the Indian-born executive part of a top-level management team that includes Ron Fisher, a 20-year SoftBank veteran. Son, 57, also anointed Arora, 47, his likely successor as CEO, though he has no plans to retire.

Arora, who was in Japan for the announcement, returned mid-week to Silicon Valley, where he is based. He answered questions about his role at SoftBank, the nature of his relationship with Son, and the future for SoftBank’s risky acquisition of the laggard U.S. telecommunications company Sprint.